If you experience knee pain, you’re probably not wondering what type of pain it is. In fact you may not even know there are two basic types of athletic sport injuries: acute and chronic. Acute injuries are brief, occur rapidly, and the cause is usually obvious. They cause pain, and often result from an impact or trauma, like a sprain or collision.

Chronic injuries, on the other hand, develop slowly; they’re persistent and last long. Cause is usually muscle overuse, but may also develop if an acute injury is not properly treated or healed. Most athletes know that ice is applied to an acute injury (i.e. sprained ankle), but they may not know the best time to apply heat.

A knee injury that results in pain, tenderness, redness, skin warm to touch, swelling, or inflammation needs treatment with ice during the first 48 hours after injury. Remember, if there is swelling you have an acute injury. The immediate application of cold therapy, after injury, helps reduce swelling and pain. Ice works as a vaso-constrictor, narrowing blood vessels, which limits internal site bleeding. Apply ice, wrapped in a thin towel to the affected area for 10 minutes. You can ice an acute injury several times a day, up to three days. Just be sure to allow the skin temperature to return to normal before icing a second or third time. Athletes also use ice therapy after a run to help reduce or prevent inflammation.

The best treatment for chronic injuries or injuries with no inflammation or swelling (i.e. sore, stiff, joint pain) is usually heat. Heat, applied to muscles, helps relax tight muscles or spasms. Some athletes with chronic pain or injury may use heat before exercise to increase elasticity and stimulate blood flow. Never apply heat after exercise. However, you should apply heat in 15-20 minute increments, using lots of layers between the heat source and skin to prevent any burns. According to Quinn, “Because some injuries can be serious, you should see your doctor if your injury does not improve (or gets worse) within 48 hours.”